streq(), wcseq(): New functions to compare strings for equality

[Alejandro Colomar]

Hi Wilco,

On Fri, Aug 29, 2025 at 04:50:54PM +0000, Wilco Dijkstra wrote:
> Hi Alejandro,
> 
> If it were an inline function or macro it seems fine as syntactic sugar.
> However I think it would be wrong to define this as an exported symbol
> that must be supported by libraries - either you end up with 2 copies of
> strcmp (bad) or you end up calling a small streq function which calls
> strcmp and adjusts the return value (also bad).

It doesn't need to be a symbol.  I think it would be fine as an inline
function.  (I'd prefer an inline function over a macro.)

> 
> Eg. on AArch64 streq looks like:
> 
> streq:
>         stp     x29, x30, [sp, -16]!
>         mov     x29, sp
>         bl      strcmp
>         cmp     w0, 0
>         ldp     x29, x30, [sp], 16
>         cset    w0, eq
>         ret

Alternatively, you could implement streq without calling strcmp, and
maybe that would be smaller/faster than strcmp(3)?


Have a lovely day!
Alex

> That's a lot of extra overhead, so most people would continue using
> 
> #define streq(X,Y) strcmp(X,Y) == 0
> 
> as that's simpler and faster.
> 
> Inlined it would essentially become a nop - and it would make it possible
> to add a new symbol similar to __memcmpeq to enable implementations
> that only provide eq/ne return value.

-- 
<https://www.alejandro-colomar.es>
Use port 80 (that is, <...:80/>).
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